全文获取类型
收费全文 | 1504篇 |
免费 | 75篇 |
国内免费 | 7篇 |
学科分类
工业技术 | 1586篇 |
出版年
2023年 | 12篇 |
2022年 | 3篇 |
2021年 | 46篇 |
2020年 | 20篇 |
2019年 | 32篇 |
2018年 | 31篇 |
2017年 | 48篇 |
2016年 | 43篇 |
2015年 | 24篇 |
2014年 | 44篇 |
2013年 | 85篇 |
2012年 | 93篇 |
2011年 | 95篇 |
2010年 | 59篇 |
2009年 | 69篇 |
2008年 | 70篇 |
2007年 | 60篇 |
2006年 | 71篇 |
2005年 | 58篇 |
2004年 | 41篇 |
2003年 | 51篇 |
2002年 | 51篇 |
2001年 | 33篇 |
2000年 | 46篇 |
1999年 | 44篇 |
1998年 | 64篇 |
1997年 | 47篇 |
1996年 | 48篇 |
1995年 | 27篇 |
1994年 | 26篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 20篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 12篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有1586条查询结果,搜索用时 31 毫秒
81.
This paper presents an efficient policy for AGV and part routing in semiconductor and LCD production bays using information on the future state of systems where AGVs play a central role in material handling. These highly informative systems maintain a great deal of information on current and near-future status, such as the arrival and operation completion times of parts, thereby enabling a new approach for production shop control. Efficient control of AGVs is vital in semiconductor and LCD plants because AGV systems often limit the total production capacity of these very expensive plants. With the proposed procedure, the cell controller records the future events chronologically and uses this information to determine the destination and source of parts between the parts' operation machine and temporary storage. It is shown by simulation that the new control policy reduces AGV requirements and flow time of parts. 相似文献
82.
Hyun Suk Suh Ju Young Ha Ji Hwan Yoon Chang-Sik Ha Hongsuk Suh Il Kim 《Reactive and Functional Polymers》2010,70(5):288-293
Ring-opening copolymerizations of propylene oxide (PO) with cyclic acid anhydrides, succinic anhydride (SA), maleic anhydride (MA) and phthalic anhydride (PA) were carried out in the presence of a double metal cyanide (DMC) catalyst of molecular formula Zn2.3Cl1.0[Co(CN)6]1.0?2.0tBuOH?1.0H2O as a means of developing functional polyols bearing ester backbones. Uniform alternating copolymers are produced when [PO]/[anhydride] in the copolymer approaches unity. All resulting copolymers have moderate molecular weights (Mn = 2300–10,600) and a narrow polydispersity index (1.02–1.49). The apparent reactivity ratio of PO is 0.34, 0.28, and 0.26 for PO/SA, PO/MA, and PO/PA copolymerizations, respectively, assuming that the reactivity ratio of the anhydrides is zero. The DMC-catalyzed PO copolymerizations with anhydrides are an efficient way to produce polyester polyols, expanding the versatility of conventional polyols. 相似文献
83.
Decision on the memory size of embedded information systems in an ubiquitous maintenance environment
Over the last decade, emerging information communication technologies have changed our stereotype of manufacturing and service companies. Now products equipped with embedded systems can be wirelessly networked, which leads to gathering and analyzing product status, and taking appropriate actions for maintenance operations during product lifecycle in an ubiquitous way. In this environment, it is necessary to determine the appropriate memory size of embedded systems for minimizing total maintenance system costs because the memory cost is a main cost factor for implementing the ubiquitous maintenance environment. We call it memory size decision problem in this study. We have formulated this problem with a non-linear model having constraints. The decision variable is the memory size of each embedded system. To solve this problem, we have proposed a meta heuristic search method based on genetic algorithms. To show the usefulness of the proposed heuristic, we have carried out computational experiments. 相似文献
84.
Suh K.S. Hyung Jae Lee Dai Soo Lee Chang Gyun Kang 《Dielectrics and Electrical Insulation, IEEE Transactions on》1995,2(3):460-466
The formation of space charge in polycarbonate (PC)/poly (styrene-co-acrylonitrile) (SAN) blends containing poly (ϵ-caprolactone) (PCL) as a compatibilizer for improving the miscibility, has been studied by measuring spatial charge distributions. It is found that the miscibility of PC/SAN blends is improved as the PCL content increases. The amount of charge accumulated in the blends decreases when the PCL content increases to 15% by weight and then increases when the PCL content is >15% wt. The decrease of charge at the PCL content <15% wt was attributed to the combined effects of changes in conductivities and the molecular interactions at the domain interfaces. The increase of charge at the PCL content >15% wt was attributed to the trapping of charge at the amorphous and crystalline phases of PC and PCL 相似文献
85.
In this paper, we investigate the effect of water (H2O) molecules evolving from silicon dioxide (SiO2) film deposited by low pressure chemical vapor deposition (LPCVD) at 670 °C on the transistor characteristic of an electrically erasable programmable read only memory (EEPROM) cell. Fourier Transform Infra red (FT-IR) analysis reveals that H2O is captured during film deposition and diffused to silicon surface during high thermal processing. The diffused H2O molecules lower threshold voltage (Vt) of cell transistor and, thus, leakage current of the cell transistor is increased. In erased cell, Vt lowering is 0.25 V in which it increases leakage current of cell transistor from 1 to 100 pA. This results in the lowering of high voltage margin of a 512 Kb EEPROM from 2.8 to 2.6 V at 85 °C. 相似文献
86.
Suh DM Kim WW Chung JG 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1999,46(2):457-463
Bolt degradation has become a major issue in the nuclear industry since the 1980's. If small cracks in stud bolts are not detected early enough, they grow rapidly and cause catastrophic disasters. Their detection, despite its importance, is known to be a very difficult problem due to the complicated structures of the stud bolts. This paper presents a method of detecting and sizing a small crack in the root between two adjacent crests in threads. The key idea is from the fact that the mode-converted Rayleigh wave travels slowly down the face of the crack and turns from the intersection of the crack and the root of thread to the transducer. Thus, when a crack exists, a small delayed pulse due to the Rayleigh wave is detected between large regularly spaced pulses from the thread. The delay time is the same as the propagation delay time of the slow Rayleigh wave and is proportional to the site of the crack. To efficiently detect the slow Rayleigh wave, three methods based on digital signal processing are proposed: wave shaping, dynamic predictive deconvolution, and dynamic predictive deconvolution combined with wave shaping. 相似文献
87.
Sols containing well-mixed tetraethyl orthosilicate, sodium methylate (CH3 ONa), and Ca metal dissolved in HCIO4 were hydrolyzed at low pH. After gelation, controlled drying, and subsequent firing at 600°C, the mixture yielded clear glass chunks. Glasses containing 85% to <100% SiO2 , which otherwise are difficult to make by conventional melting techniques, could be made using this technique. 相似文献
88.
89.
JS Chang DY Noh IA Park MJ Kim H Song SH Ryu PG Suh 《Canadian Metallurgical Quarterly》1997,57(24):5465-5468
Phospholipase C-gamma1 (PLC-gamma1) mediates signals from various extracellular origins to evoke cellular events such as mitogenesis. Previously, we reported that PLC-gamma1 was highly expressed in colorectal cancer and familial adenomatous polyposis, suggesting that PLC-gamma1 might be oncogenic. In this study, we have established rat 3Y1 fibroblasts that overexpress whole PLC-gamma1 and src homology 2 (SH2)-SH2-SH3 domain of PLC-gamma1. These cells showed a transformed phenotype and were tumorigenic when transplanted into nude mice. These results indicate that overexpression of PLC-gamma1 could transform rat fibroblasts, and the transformation is mediated by SH2-SH2-SH3 domain of PLC-gamma1. 相似文献
90.
We compared the dose-response relationships of cisatracurium, mivacurium, atracurium, vecuronium and rocuronium and examined the interactions of cisatracurium with mivacurium, atracurium, vecuronium and rocuronium in humans by isobolographic and fractional analyses. We studied 180 adult patients during nitrous oxide-fentanyl-propofol anaesthesia. Neuromuscular block was monitored using mechanomyography to detect the twitch response of the ulnar nerve at the wrist. The dose-response curves were determined by probit analysis. The calculated ED50 values and their 95% confidence intervals were 40.9 (38.1-43.7), 49.8 (47.0-52.6), 187.2 (175.1-199.3), 36.6 (34.7-38.5) and 136.4 (129.2-143.6) micrograms.kg-1 for cisatracurium, mivacurium, atracurium, vecuronium and rocuronium, respectively. Corresponding ED95 values were 57.6 (53.5-61.7), 91.8 (88.1-95.5), 253.1 (238.9-267.3), 52.9 (49.1-56.7) and 288.7 (276.2-301.2) micrograms.kg-1, respectively. The interaction between cisatracurium and mivacurium, vecuronium or rocuronium was found to be synergistic, but the interaction between cisatracurium and atracurium was found to be additive. Synergy between cisatracurium and vecuronium or rocuronium was greater than between cisatracurium and mivacurium. 相似文献